GB1012857A - Liquid fuel injection pumps for internal combustion engines - Google Patents

Abstract

1,012,857. Fuel injection pumps. C.A.V. Ltd. May 6, 1964 [May 24, 1963], No. 20770/63. Headings F1A and F1B In a fuel injection pump comprising a rotary distributor 11 having a bore 17 formed therein housing pump pistons 18, the pistons being moved outwardly by fuel fed to the bore by shuttles 27 and 28 and inwardly by a cam 20, the maximum outward movement of the shuttle 28 is determined by the output pressure of the feed pump 12. The feed pump supplies fuel alternately to opposite ends of the shuttles 27 and 28 at a pressure dependent on the speed of the engine being supplied and their outward movement is determined by a throttle 33 to a maximum determined by stops 38 and 39 respectively. The stop 38 remains fixed during operation of the pump and the stop 39, biased by a spring 41, is subject to the outlet pressure of the feed pump 12 via fuel outlet 14, Fig. 2. The stop 39 is of profiled form to reduce the maximum outward movement of the shuttle 28 as the fuel pressure increases. The outer end of the shuttle 28 is placed in communication with the inlet 13 of the feed pump during rotation of the distributor 11 and the shuttle 27 similarly by means of a passage 42a and a port 42 communicating with the outer end of the shuttle 28. At starting with zero-fuel pressure the member 39 is positioned to permit the shuttle 28 to move to the maximum extent provided a recess 43 in the member 39, the member closes the port 42 and shuttle 28 uncovers a passage 44a, Fig. 6, to allow fuel to flow directly into the bore 17 and provide excess fuel for starting. With rise in pressure the passage 44a is closed by the shuttle, the port 42 uncovered by the member 39 and the quantity of fuel delivered is governed by movement of the shuttles. The injection timing of the engine is varied by a spring-loaded piston 45, Fig. 5, subject to the outlet pressure of the feed pump.